Hymeraphia stellifera (Bowerbank, 1866)


Family : Raspailiidae

Form: Very thin sheet, almost impossible to remove from the substratum except in tiny pieces.

Colour: Typically orange/red.

Smell: None.

Consistency: Too thin to determine.

Surface: Usually silt covered with regularly spaced red raised bumps showing through, occasionally clean with these raised bumps. Villose, due to scattered long spicules which penetrate the surface.

Apertures: The oscules are small, at the summits of the raised bumps mentioned above. No ostia visible.

Contraction: None, difficult to determine.

Internal characters

Skeleton: The skeleton consists of a basal layer of short, stout tylostyles with distinctive outer ends consisting of a ball of spines, mixed with scattered long tylostyles which penetrate the surface. Where the latter penetrate the surface there is a brush of fine styles. (see skeletal drawing for Eurypon major.)

Spicules: Three categories of megasclere and no microscleres are present. The largest megascleres are long tylostyles with rounded heads and smooth shafts. Shorter tylostyles with distinctive spined ends and flask-shaped rounded heads are abundant. Fine, thin styles are freqent, forming brushes at surface.

Habitat: Mostly found in deeper water, below 30 metres, but occasionally as shallow as 20m. Tolerant of silt, and found in sheltered places on dead shells as well as on bedrock in both exposed and sheltered locations.

Distribution: "British Isles; France; Mediterranean." Known recently from Strangford Lough, St Kilda, Skomer, Stags of Broadhaven, Co Mayo, Lough Hyne. Probably common but rarely recorded because of its extremely thin nature.

Distribution Map: NBN map : National Biodiversity Network mapping facility, data for UK.

Identity: The short spicules with spined ends are very distinctive and are not found in any other British species. In the field the thin red sheet, often silt-covered, is difficult to distinguish from some Eurypon species, but it is even thinner than most of these.

Editors: B.E. Picton

 Picton, B.E., Morrow, C.C. & van Soest, R.W.B., 2011. [In] Sponges of Britain and Ireland